It has been asked before, but with different answers, e.g.:
1) dpkg-query --list | awk '/^ii +/ { print $2; }'
2) dpkg --get-selections | cut -f 1
3) ... etc ...
Given that the output is the same:
$ diff \
<(dpkg --get-selections | cut -f 1) \
<(dpkg-query --list | awk '/^ii +/ { print $2; }') \
&& echo same-output
same-output
I wonder, what's the golden way to do this and why?